Messages in this thread | | | Date | Mon, 6 Mar 2023 14:47:55 +0000 | From | Mark Rutland <> | Subject | Re: [PATCH] arm64: smccc: Add trace events to SMC calls. |
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On Sat, Mar 04, 2023 at 06:28:50PM +0530, Rakesh Babu Saladi wrote: > This patch adds start and end trace events to an SMC call sent from > kernel to ATF. The start trace event prints the smc_id and the end > trace event prints the smc_id and the time taken to process the SMC > call. > > Signed-off-by: Rakesh Babu Saladi <rsaladi2@marvell.com>
We've said no to this in the past:
https://lore.kernel.org/lkml/20210923112058.GA14893@C02TD0UTHF1T.local/
I don't think anything has changed, and this has all the same problems as before, so I do not think we should do this.
Which SMC calls do you want to trace, and why?
Thanks, Mark.
> --- > drivers/firmware/smccc/Makefile | 3 +- > drivers/firmware/smccc/smccc.c | 14 ++++++++++ > drivers/firmware/smccc/smccc_trace.c | 7 +++++ > drivers/firmware/smccc/smccc_trace.h | 41 ++++++++++++++++++++++++++++ > include/linux/arm-smccc.h | 4 ++- > kernel/time/timekeeping.c | 7 +++++ > 6 files changed, 74 insertions(+), 2 deletions(-) > create mode 100644 drivers/firmware/smccc/smccc_trace.c > create mode 100644 drivers/firmware/smccc/smccc_trace.h > > diff --git a/drivers/firmware/smccc/Makefile b/drivers/firmware/smccc/Makefile > index 40d19144a860..e74c35191b49 100644 > --- a/drivers/firmware/smccc/Makefile > +++ b/drivers/firmware/smccc/Makefile > @@ -1,4 +1,5 @@ > # SPDX-License-Identifier: GPL-2.0 > # > -obj-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smccc.o kvm_guest.o > +ccflags-y += -I$(src) > +obj-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smccc_trace.o smccc.o kvm_guest.o > obj-$(CONFIG_ARM_SMCCC_SOC_ID) += soc_id.o > diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c > index 60ccf3e90d7d..7631a16479e9 100644 > --- a/drivers/firmware/smccc/smccc.c > +++ b/drivers/firmware/smccc/smccc.c > @@ -11,6 +11,7 @@ > #include <linux/kernel.h> > #include <linux/platform_device.h> > #include <asm/archrandom.h> > +#include "smccc_trace.h" > > static u32 smccc_version = ARM_SMCCC_VERSION_1_0; > static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE; > @@ -59,3 +60,16 @@ static int __init smccc_devices_init(void) > return 0; > } > device_initcall(smccc_devices_init); > + > +void arm_smccc_smc(unsigned long a0, unsigned long a1, unsigned long a2, unsigned long a3, > + unsigned long a4, unsigned long a5, unsigned long a6, unsigned long a7, > + struct arm_smccc_res *res) > +{ > + u64 start, elapsed; > + > + trace_arm_smccc_smc_start(a0); > + start = ktime_get_ns(); > + __arm_smccc_smc(a0, a1, a2, a3, a4, a5, a6, a7, res, NULL); > + elapsed = ktime_get_ns() - start; > + trace_arm_smccc_smc_end(a0, elapsed); > +} > diff --git a/drivers/firmware/smccc/smccc_trace.c b/drivers/firmware/smccc/smccc_trace.c > new file mode 100644 > index 000000000000..6b94d5d9c0f4 > --- /dev/null > +++ b/drivers/firmware/smccc/smccc_trace.c > @@ -0,0 +1,7 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#define CREATE_TRACE_POINTS > +#include "smccc_trace.h" > + > +EXPORT_TRACEPOINT_SYMBOL(arm_smccc_smc_start); > +EXPORT_TRACEPOINT_SYMBOL(arm_smccc_smc_end); > diff --git a/drivers/firmware/smccc/smccc_trace.h b/drivers/firmware/smccc/smccc_trace.h > new file mode 100644 > index 000000000000..c0ef836bc093 > --- /dev/null > +++ b/drivers/firmware/smccc/smccc_trace.h > @@ -0,0 +1,41 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > + > +#undef TRACE_SYSTEM > +#define TRACE_SYSTEM smccc > + > +#if !defined(__SMCCC_TRACE_H) || defined(TRACE_HEADER_MULTI_READ) > +#define __SMCCC_TRACE_H > + > +#include <linux/types.h> > +#include <linux/tracepoint.h> > + > +TRACE_EVENT(arm_smccc_smc_start, > + TP_PROTO(unsigned long smc_id), > + TP_ARGS(smc_id), > + TP_STRUCT__entry(__field(unsigned long, smc_id)), > + TP_fast_assign(__entry->smc_id = smc_id;), > + TP_printk("SMC ID: 0x%lx", __entry->smc_id) > +); > + > +TRACE_EVENT(arm_smccc_smc_end, > + TP_PROTO(unsigned long smc_id, u64 elapsed_time), > + TP_ARGS(smc_id, elapsed_time), > + TP_STRUCT__entry(__field(unsigned long, smc_id) > + __field(u64, elapsed_time) > + ), > + TP_fast_assign(__entry->smc_id = smc_id; > + __entry->elapsed_time = elapsed_time; > + ), > + TP_printk("SMC ID: 0x%lx time taken to process : %llu ns", > + __entry->smc_id, __entry->elapsed_time) > +); > + > +#endif /* __SMCCC_TRACE_H */ > + > +#undef TRACE_INCLUDE_PATH > +#define TRACE_INCLUDE_PATH . > + > +#undef TRACE_INCLUDE_FILE > +#define TRACE_INCLUDE_FILE smccc_trace > + > +#include <trace/define_trace.h> > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h > index 220c8c60e021..39588c3db486 100644 > --- a/include/linux/arm-smccc.h > +++ b/include/linux/arm-smccc.h > @@ -358,7 +358,9 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1, > unsigned long a5, unsigned long a6, unsigned long a7, > struct arm_smccc_res *res, struct arm_smccc_quirk *quirk); > > -#define arm_smccc_smc(...) __arm_smccc_smc(__VA_ARGS__, NULL) > +void arm_smccc_smc(unsigned long a0, unsigned long a1, unsigned long a2, > + unsigned long a3, unsigned long a4, unsigned long a5, > + unsigned long a6, unsigned long a7, struct arm_smccc_res *res); > > #define arm_smccc_smc_quirk(...) __arm_smccc_smc(__VA_ARGS__) > > diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c > index 5579ead449f2..3a3bf2d674a3 100644 > --- a/kernel/time/timekeeping.c > +++ b/kernel/time/timekeeping.c > @@ -192,6 +192,13 @@ static inline u64 tk_clock_read(const struct tk_read_base *tkr) > { > struct clocksource *clock = READ_ONCE(tkr->clock); > > + /* At the time of kernel booting some SMC calls are called before the > + * clock is initialized, in such cases it would lead to kernel crash. > + * To prevent kernel crash in such cases this check is included. > + */ > + if (unlikely(!clock)) > + return 0; > + > return clock->read(clock); > } > > -- > 2.17.1 >
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